<div class="container"></div>

<style>
/* From Uiverse.io by csemszepp - Source: https://github.com/Afif13 - Website: https://github.com/Afif13  - Name: Afif13  - Tags: simple, material design, pattern */
.container {
  width: 100%;
  height: 100%;
  --s: 200px; /* control the size */
  --c1: #1d1d1d;
  --c2: #4e4f51;
  --c3: #3c3c3c;

  background: repeating-conic-gradient(
        from 30deg,
        #0000 0 120deg,
        var(--c3) 0 180deg
      )
      calc(0.5 * var(--s)) calc(0.5 * var(--s) * 0.577),
    repeating-conic-gradient(
      from 30deg,
      var(--c1) 0 60deg,
      var(--c2) 0 120deg,
      var(--c3) 0 180deg
    );
  background-size: var(--s) calc(var(--s) * 0.577);
}

</style>
    